The present invention relates to a semiconductor device and a method of forming the same and, more particularly, to a fuse of a semiconductor device, which are capable of minimizing the migration of copper (Cu) after a blowing process.
A semiconductor device, such as a memory device and memory merged logic (MML), includes numerous memory cells for storing data. If any one of the memory cells is faulty, the entire semiconductor device is determined to be faulty, resulting in a lowered yield. However, to discard the entire semiconductor device as being a faulty product although only some of the cells have failed is wasteful. Accordingly, a memory device or a semiconductor device including a large amount of memory requires a repair function in order to secure a higher yield. The repair method in semiconductor devices is chiefly a method of replacing a faulty memory cell with a redundant memory cell. In order to replace the faulty memory cell with the redundant memory cell, fuses that can cut a line are used. Accordingly, a number of fuses are used in the semiconductor device, and the fuses can be cut using a laser. These fuses can be selectively cut according to the test results.
A repair method using a redundant cell uses the word line of the redundant cell for replacing a word line of a failed cell and a bit line of the redundant cell for replacing a bit line of a failed cell. To this end, a memory device includes a circuit for replacing an address of the faulty cell with an address of the redundant cell when the faulty cell is detected through a test after wafer processing. Accordingly, if the cell address corresponding to the faulty cell is inputted when the memory device is used, data of the reserved cell that has replaced the faulty cell is accessed.
A typical repair method changes the path of an address by blowing a fuse using a laser beam. Accordingly, a typical memory device is manufactured with a fuse region for changing an address path by blowing the fuse using a laser. A fuse includes a wiring line designed to be blown by the irradiation of the laser, and a fuse box includes a region including the fuse and its periphery.
In the fuse blowing process an insulating layer having a specific thickness covers the fuse and the fuse of a failed cell is then cut by irradiating with a laser. In this case, the laser energy passes through the insulating layer without being absorbed because the insulating layer has the same properties as glass. Thus, most of the laser energy is absorbed by the fuse. The fuse is thermally expanded by the laser energy, and so the fuse is blown and cut. In other words, after the blowing process, the fuse that has absorbed the laser energy must be completely evaporated and removed through the air.
However, if the fuse is not completely evaporated, residue remains in the fuse blowing region, which may result in a reconnection of the fuse ends. In this case, an address repair process is not properly performed because a fuse that should have been cut is still electrically connected. A similar problem can occur when fuse metals (e.g., copper) migrate under high temperature and high humidity conditions, resulting in a reconnection of the fuse ends.